BMW 5 Series E39

since 1996-2001 release

Repair and operation of the car

+ Introduction
+ Maintenance instruction
+ Current leaving and service
+ Engine
- Cooling systems, heating
   - Cooling system
      Check of the cooling system
      Removal, installation and check of the thermostat
      Removal and installation of the fan and coupling of the fan
      Removal and installation of a broad tank
      Removal and installation of a radiator
      Removal and installation of the pump of cooling liquid
   + Heater
   + Air conditioner
+ Power supply system and release
+ Engine electric equipment
+ Manual transmission
+ Automatic transmission
+ Coupling and power shafts
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment
+ Schemes of electric equipment
+ System of onboard diagnostics

Removal, installation and check of the thermostat

The thermostat at increase of temperature of the engine connects a big contour of cooling. If the thermostat owing to damage remains closed, the engine overheats. A sign of it is the index of temperature which is in red range. At the same time cooling liquid remains cold. The faulty thermostat after cooling of liquid can remain open. A sign of it is the impossibility of achievement by the engine of working temperature or slower growth of temperature of cooling liquid, than still, and in the winter - falling of power of a heater.

If the engine heats up after the small run of the car, also pollution of a radiator owing to lime deposits can be the cause.


Model 525tds

1 — the thermostat case
2 — a ventilation bolt
3 — the thermostat

4 — a sealing ring
5 — a bolt

Models 520i, 523i, 528i

1 — the thermostat case
2 — the thermostat
3 — a sealing ring

4 — consolidation
5 — M6 bolt
6 — M8 bolt


1. Remove the fan, address the Section Removal and installation of the fan and coupling of the fan.
2. Merge cooling liquid, address the Section Cooling System Liquid Replacement. Check of frost resistance of a cooler. Visual check of the cooling system.
3. Disconnect hoses from the thermostat case (from the forward party of the block of cylinders). For this purpose open collars.

4. Models 520i, 523i, 528i: Remove lifting eyes from the engine. Disconnect the mine of a cable at clips and remove. Address an accompanying illustration.

5. Turn off a thermostat cover.

Bolts of fastening have various length, it is recommended to write down their lengths.

6. Pay attention to position of the thermostat and take out it.


1. Heat the thermostat in the container with water. At the same time the thermostat should not concern capacity walls. Temperature is taken by the corresponding thermometer. Address an accompanying illustration.

2. At a temperature about +88 °C the gate of the thermostat begins to open. The beginning of opening is visible on the thermostat.
3. Check whether the thermostat extends and whether it is closed and also whether the beginning of opening coincides with the established value specified on the thermostat. If necessary replace the thermostat.


1. Clear sealing surfaces on the case and a cover.

2. Models 520i, 523i, 528i: Insert the thermostat into a head of cylinders so that the arrow showed up. Address an accompanying illustration.

3. 525tds: Insert the thermostat so that the ventilating valve showed upward. The arrow is in a cover groove. Address an accompanying illustration.

4. Slightly grease a sealing ring of the thermostat with glycerin and establish it, address an illustration in the subsection "Removal".
5. 520i, 523i, 528i: Paper laying needs to be established surely new.
6. Install the case of the thermostat and evenly wrap fastening bolts the moment specified in Specifications.

Do not tighten bolts too strongly. Do not forget to establish load-lifting eyes at the 6-cylinder engine.

Tighten bolts of fastening of an eye (M8) the moment of 20 Nanometers.

7. Fix the mine of a cable by clips.
8. Install the fan and a cover of the fan.
9. Fill system with liquid and remove air, address the Section Cooling System Liquid Replacement. Check of frost resistance of a cooler. Visual check of the cooling system.
10. Start and warm up the engine so that viscous coupling connected the fan. Check whether the radiator in the lower part got warm and check tightness of the case of the thermostat. With leakage tighten fastening bolts.